1. Field of the Invention
The present invention relates generally to improvements in the design and operation of article handling apparatus and is particularly useful in the environment of article handling devices that use a suction-type article handling mechanism including a quick release device.
2. Description of the Prior Art
Most prior art article handling mechanisms, more specifically referred to in the description of the present invention as being in the environment of a point-of-sale (POS) article dispenser, rely on a multitude of motors, switches and solenoids for moving various portions of the handling mechanism, and handling of the articles themselves, such as packaged products. Most machines of this type require one motor, switch and/or solenoid dedicated for each row, column or type of article or package to be handled or dispensed therefrom. Such machines generally suffer from numerous disadvantages, such as poor reliability due to mechanical failures, as well known by those skilled in this art.
U.S. Pat. No. 5,240,139 represents a significant improvement in article handling devices. It describes the use of a negative air pressure lifter (i.e., article pickup or handling mechanism), which uses suction, i.e., a reduced or so-called “negative” air pressure created by a partial vacuum, for making a secure contact to an article to be retrieved by entering the open top of an article storage bin located in a refrigerated storage area of a vending machine. Although robotic, and specifically suction-type lifting mechanisms are in common use in factory settings, where space limitations are generally relaxed, their use in tight confines, such as an article vending machine, has not gained wide acceptance. Due to the greater reliability and versatility of vending machines of the type which utilizes suction technology for grasping and moving selected articles, it would be desirable to develop new techniques and methods for the operation and control of such machines, as well as for other more generalized article handling mechanisms.
Article contact detection is provided in the forenoted U.S. Pat. No. 5,240,139 by a mechanical or electromechanical proximity switch mounted at the article pickup end of the negative air pressure lifter.
It is desirable to avoid the use of a proximity switch type of sensor at the article pickup end of the lifter, most notably because of the necessity of providing to the pickup head electrical power and signal carrying conductors necessary for operating the switch. Such conductors not only may present obstacles to the freedom of movement of the pickup head, but may also present reliability problems due to their potential for breakage.
Applicant's patent application PCT/US01/16916 entitled METHOD AND APPARATUS FOR ARTICLE CONTACT DETECTION IN AN ARTICLE HANDLING DEVICE, filed May 23, 2001, describes an article dispensing apparatus embodied, for example, as a vending machine, which includes a controllably positioned suction hose dispenser for retrieving articles from a storage area. In one embodiment, a sensor having an output responsive to changes in partial pressure inside the air hose, such as an airflow sensor coupled to the suction-hose, initially acts to sense the timing of contact of the suction hose with an article to be dispensed. As long as suction is provided to the gripping end of the suction hose prior to the hose contacting the article to be retrieved, the airflow (and partial pressure) inside the hose will change dramatically when the gripping end of the suction hose makes contact with the article. At the moment when the gripping end of the suction hose is no longer in substantial contact with the article, the airflow sensor again provides an indication signal, due to the sudden change in airflow (and partial pressure) that occurs at that time within the hose. The signals generated by the airflow sensor are used in place of those generated by the prior art mechanically operated proximity sensor, and may be used to stop the approach of the gripping end of the hose towards the article, and serve as an indication to initiate removal of the article from the storage area. Alternatively, the airflow sensor can be used in conjunction with the proximity sensor, as a further check of the proper operation of the suction generating portion of the dispenser apparatus, since the airflow sensor actually monitors air flow.
In the above embodiment, the airflow sensor is used to operate an airflow control mechanism, i.e., a vacuum or suction release (i.e., vacuum breaker), to facilitate a “quick-release” of the article being handled. The airflow sensor can be included in its own housing, or as in the illustrated embodiment, a housing which also includes therein the vacuum release/breaker mechanism. In one embodiment, the vacuum release mechanism comprises a movable flap which in its normal position seals an opening in a sidewall of the airflow housing. A mechanical “see-saw”-type linkage mounted in the top of the front door of the vending machine cabinet is used to activate the vacuum release mechanism in response to mechanical contact by the article handling mechanism when it reaches the dispensing area. Contact at one end of the linkage causes linkage at the other end to move the flap and unseal the opening in the airflow housing.
The present invention is directed to improvements in the design and operation of a mechanical linkage which can be used, in one embodiment, to activate a vacuuum release/breaker mechanism in response to movemement of the article handling mechanism.